The invention relates to an arc extinguishing chamber for an electrical switchgear device, notably a circuit breaker or a current limiting unit, comprising:
a system of stationary and movable contacts, housed inside an almost tightly sealed case made of insulating material, the movable contact being biased to the open position by the pressure generated by the arc drawn between the contacts after separation,
a compression piston separated from the walls of the case by a predetermined clearance J subdividing the internal volume of the case into a first compartment generating pressure due to the action of the arc, and a second compartment communicating with said first compartment via the clearance J, the volumes of the two elementary compartments varying inversely with one another when movement of the movable contact occurs.
In a device of this nature, electric arc extinction is not achieved by deionization by means of stacked metal separators, but results from the pressure generated by the arc itself. According to the document EP-A-No. 87642, separation of the contacts is accomplished by the action of an excitation coil arranged coaxially around the contacts and inserted in series electrically with the latter. The movable contact is made of magnetic material, and the case comprises a plurality of exhaust slots designed to reduce the pressure inside the case.
The object of the invention consists in making a high pressure arc extinguishing chamber for a low voltage switchgear device easier to achieve.